Rotor for rotary electric machine

Abstract

A rotor for a rotary electric machine has a plurality of magnetic poles provided at intervals in a circumferential direction of a rotor core, at an outer periphery of the rotor core. Each of the magnetic poles includes a central magnet, a pair of circumferential-direction magnets disposed on both sides of the central magnet in the circumferential direction such that a spacing between the pair widens towards an outer periphery of the rotor core, and low permeability regions provided in the vicinity of end portions of the central magnet in the circumferential direction, and having a permeability lower than a magnetic material of the rotor core. The rotor core is formed such that a width of a magnetic path entrance portion that is formed between a magnetic-pole inward side face of the circumferential-direction magnet and the adjacent low permeability region decreases towards an outer peripheral face of the rotor core.

What is claimed is: 
     
       1. A rotor for a rotary electric machine, comprising:
 a rotor core including a plurality of magnetic poles provided at intervals in a circumferential direction of the rotor core and at an outer periphery of the rotor core, wherein 
 each of the magnetic poles includes: 
 a central magnet provided in the vicinity of an outer peripheral face of the rotor core, 
 a pair of circumferential-direction magnets disposed on both sides of the central magnet in the circumferential direction such that a mutual spacing between the pair widens towards an outer periphery of the rotor core, 
 a pocket portion having a lower permeability than that of a magnetic material of which the rotor core is made, disposed at an outer periphery side of each of the circumferential-direction magnets, and 
 a low permeability region provided in the vicinity of each of end portions of the central magnet in the circumferential direction, and having a permeability lower than that of the magnetic material, of which the rotor core is made, and 
 the rotor core is formed in such a manner that a width of a magnetic path entrance portion that is formed between a magnetic-pole inward side face, which is an inward side face of each of the circumferential-direction magnets and an inward side face of each of the pocket portions in the circumferential direction of the magnetic pole, and the low permeability region adjacent to the magnetic-pole inward side face becomes narrower towards the outer peripheral face of the rotor core, where the magnetic-pole inward side face has a straight-line shape formed by one inward side face of the circumferential-direction magnet and one inward side face of the pocket portion. 
 
     
     
       2. The rotor for a rotary electric machine according to  claim 1 , wherein a cross section, perpendicular to an axial direction of the rotor core, of each of the central magnet and the pair of circumferential-direction magnets, has an elongated rectangular shape. 
     
     
       3. The rotor for a rotary electric machine according to  claim 2 , wherein the width of the magnetic path entrance portion is a width in a direction perpendicular to a longitudinal direction of the elongated rectangular shape. 
     
     
       4. The rotor for a rotary electric machine according to  claim 1 , wherein
 the low permeability region includes a hole formed in the rotor core; 
 the hole has a straight-line shaped edge portion that is opposed to the magnetic-pole inward side face of the circumferential-direction magnet, across the magnetic path entrance portion; and 
 the edge portion of the low permeability region extends in a direction that forms a predetermined angle with respect to an imaginary straight line that passes through an inner-periphery-side end portion of the edge portion and is parallel to the magnetic-pole inward side face of the circumferential-direction magnet. 
 
     
     
       5. The rotor for a rotary electric machine according to  claim 4 , wherein
 the hole is a through-hole of substantially triangular shape formed so as to pass through the rotor core in the axial direction, in the vicinity of the end portion of the central magnet in the circumferential direction; 
 the edge portion of the low permeability region is a side edge portion of the through-hole; and 
 the through-hole is adjacent to a second pocket portion, which is a low-permeability portion formed on each side of the central magnet in the circumferential direction, with a bridge portion of the rotor core interposed between the through hole and the pocket portion. 
 
     
     
       6. The rotor for a rotary electric machine according to  claim 1 , wherein the magnetic pole further includes a magnetic flux suppression hole that is formed between inner-periphery-side end portions of the pair of circumferential-direction magnets, in a radial direction of the rotor core, so as to extend inward in the radial direction. 
     
     
       7. The rotor for a rotary electric machine according to  claim 1 , wherein
 the magnetic pole is configured to be line-symmetrical with respect to a magnetic pole centerline, which is a radial direction line extending along a radial direction of the rotor core and passing through a center of the magnetic pole in the circumferential direction. 
 
     
     
       8. The rotor for a rotary electric machine according to  claim 1 , wherein the magnetic path entrance portion is a core region that is part of the rotor core. 
     
     
       9. The rotor for a rotary electric machine according to  claim 1 , wherein a part of the magnetic flux generated from an outer peripheral end portion of the central magnet flows to an inner periphery side portion of the magnetic path entrance portion.